Developing device, cartridge, image forming apparatus

A developing device includes a frame having an accommodation chamber where a developer is accommodated, and a replenishing port replenishing a developer to the accommodation chamber from outside, and a stirring member stirring the developer in the accommodation chamber. The stirring member includes a rotating shaft portion rotatably supported by the frame and a sheet member having one end fixed to the rotating shaft portion and another end as a free end and being rotatable with the rotating shaft portion. When the stirring member is rotated, the free end of the sheet member is capable of contacting an inner wall surface of the accommodation chamber in which the replenishing port is formed, and a through hole penetrating in a thickness direction of the sheet member is provided in a region of the sheet member that comes into contact with the inner wall surface of the accommodation chamber.